An image forming apparatus includes a toner cartridge to supply toner to a developing unit. The toner cartridge includes a cartridge body to contain toner, a stirring member contained in the cartridge body, and a screw disposed at the bottom of the cartridge body. The cartridge body includes a toner discharge port to discharge toner. The stirring member rotates in the cartridge body to stir the toner so that the toner is not solidified. The screw rotates in the cartridge body to carry the toner to the toner discharge port.
The stirring member used in the related art toner cartridge includes a rotation shaft supported by the cartridge body and a paddle rotating together with the rotation shaft. The paddle includes plural rod-like members constructed like a truss. The paddle includes two outer frames extending in the axial direction of the rotation shaft. When the rotation shaft rotates, the outer frames move along the inner surface of the cartridge body.
Further, the paddle includes a scraping sheet having elasticity. The scraping sheet is fixed to the one outer frame and projects from the outer frame to the inner surface of the cartridge body. When the paddle rotates, the scraping sheet scrapes the toner adhered to the inner surface of the cartridge body, and sends the scraped toner to the screw.
In a new toner cartridge stored for a long term, toner in the cartridge body is in a compressed state. Further, when the new toner cartridge is transported, there can occur a state where the toner in the cartridge body is solidified by vibration applied to the toner cartridge. Thus, the new toner cartridge is recommended to be shaken a predetermined number of times before it is mounted to an image forming apparatus and is used. When the toner cartridge is shaken, the toner in the cartridge body is loosened and the fluidity of the toner can be raised.
However, for example, when the user does not shake the toner cartridge as specified, it is supposed that the toner is not sufficiently loosened. When the toner is not sufficiently loosened, a lump of toner is mixed in the toner, and a part of the toner remains to be adhered to the inner surface of the cartridge body. Thus, when the stirring member rotates, the resistance of the toner applied to the stirring member is increased.
Specifically, since the outer frame of the stirring member moves along the inner surface of the cartridge body, the lump of toner is bitten between the outer frame and the inner surface of the cartridge body, or the outer frame inevitably strikes against the toner adhered to the inner surface of the cartridge body. As a result, the resistance to prevent the rotation of the stirring member is applied to the outer frame, and there can occur a state the stirring member is locked.
Further, the scraping sheet is made of a flexible resin film having elasticity. The flexible scraping sheet can not break the toner adhered to the inner surface of the cartridge body. Thus, the amount of toner remaining in the cartridge body is increased, and the toner in the cartridge body can not be completely used up.